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| author | Stephen Douthit <stephend@adiengineering.com> | 2017-08-07 17:10:59 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-09-07 08:35:39 +0200 |
| commit | d22f6da47355b6547427838d67054c51bca0c011 (patch) | |
| tree | 9c82dd9e879a9d6ff9bcfbdf6e817416412514a2 /drivers/i2c | |
| parent | 31562136c8d4ed60f2b6bc1c6c349c176432470f (diff) | |
| download | linux-rt-d22f6da47355b6547427838d67054c51bca0c011.tar.gz | |
i2c: ismt: Don't duplicate the receive length for block reads
commit b6c159a9cb69c2cf0bf59d4e12c3a2da77e4d994 upstream.
According to Table 15-14 of the C2000 EDS (Intel doc #510524) the
rx data pointed to by the descriptor dptr contains the byte count.
desc->rxbytes reports all bytes read on the wire, including the
"byte count" byte. So if a device sends 4 bytes in response to a
block read, on the wire and in the DMA buffer we see:
count data1 data2 data3 data4
0x04 0xde 0xad 0xbe 0xef
That's what we want to return in data->block to the next level.
Instead we were actually prefixing that with desc->rxbytes:
bad
count count data1 data2 data3 data4
0x05 0x04 0xde 0xad 0xbe 0xef
This was discovered while developing a BMC solution relying on the
ipmi_ssif.c driver which was trying to interpret the bogus length
field as part of the IPMI response.
Signed-off-by: Stephen Douthit <stephend@adiengineering.com>
Tested-by: Dan Priamo <danp@adiengineering.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-ismt.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c index f573448d2132..8075a9368681 100644 --- a/drivers/i2c/busses/i2c-ismt.c +++ b/drivers/i2c/busses/i2c-ismt.c @@ -341,8 +341,8 @@ static int ismt_process_desc(const struct ismt_desc *desc, break; case I2C_SMBUS_BLOCK_DATA: case I2C_SMBUS_I2C_BLOCK_DATA: - memcpy(&data->block[1], dma_buffer, desc->rxbytes); - data->block[0] = desc->rxbytes; + memcpy(data->block, dma_buffer, desc->rxbytes); + data->block[0] = desc->rxbytes - 1; break; } return 0; |